I could easily imagine the Russian government shutting down internet usage for a few hours until they had a better handle on the situation. But, I have to ask, how possible is it that this was instead a lot more people than usual trying to use the internet in that area, because they were all on their smartphones trying to coordinate their activities in bandwidth-hungry ways?

Not saying it's likely, I don't know enough about the tech and infrastructure to evaluate that. Just asking the question in case somebody on HN does know.